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Proximity Effect Detection for Directional Microphones

The proximity effect in directional microphones is characterised by an undesired boost in low frequency energy as the source to microphone distance decreases. Traditional methods for reducing the proximity effect use a high pass filter to cut low frequencies which alter the tonal characteristics of the sound and are not dependent on the input source. This paper proposes an intelligent approach to detect the proximity effect in a single capsule directional microphone in real time. The low frequency boost is detected by analysing the spectral flux of the signal over a number of bands over time. A comparison is then made between the bands to indicate the existence of the proximity effect. The proposed method is shown to accurately detect the proximity effect in test recordings of white noise and of other musical inputs. This work has applications in the reduction of the proximity effect.